Puck From 'Real World' Begins Prison Sentence For Stalking

"Real World" legend David "Puck" Rainey is officially locked up in a California state prison ... TMZ has learned -- after he was convicted of stalking a woman earlier this year.

The details surrounding the stalking incident are unclear, but according to court docs, 44-year-old Rainey -- who starred in "Real World: San Francisco" in 1994 -- committed the crime on February 22nd.